1. Field of Invention
The present disclosure of invention relates to a light guide plate and a backlight unit of a liquid crystal display (LCD) panel having such a guide plate. More particularly, the present disclosure relates to a side-lit (edge lit) light guide plate capable of reducing power consumption by the side lighting light source (when selective regional or local dimming is employed) and a backlight unit having the light guide plate.
2. Description of Related Technology
Since liquid crystal displays (LCDs) and other flat panel light valve types of displays are called upon to have advantages such as slimness, light weight, and low power consumption, ways to reduce flat panel display thickness and/or power consumption have been extensively explored. The typical LCD includes an LCD panel that displays an image by selective shuttering of light, a backlight unit that supplies light to the LCD panel, and a driving circuit that applies driving signals to pixel units of the LCD panel.
Backlight units may be classified into direct-illumination type backlight units and edge-illumination type backlight units according to the methods used of supplying light from a light source to the LCD panel. In the direct-illumination type backlight unit, a plurality of light sources (e.g., fluorescent light bulbs) are provided below the LCD panel to directly supply light to the LCD panel. In the edge-illumination type backlight unit, the light sources are provided in the vicinity of a side or edge portion of the LCD panel, and light is supplied to the LCD panel by being redirected through a light guide plate.
The edge-illumination type backlight unit is conventionally maintained in an always fully turned-on state, in a homogeneous light redistributing state and thus it provides a continuously uniform level of brightness across the entire area of the display panel regardless of brightness of the image pixels being displayed on different parts of the LCD panel or regardless of dark bands that may be caused by presence of a black matrix of the LCD or the like, and thus maximal light energy is always supplied as a uniform continuum towards the LCD even if such full amount of continuously uniformly supplied light energy is not required for producing the currently displayed image, where the latter may be formed of discrete rows or columns of pixels and where the rows and/or columns may be grouped into regions that can be selectively controlled with backlight local dimming techniques in some cases.